The inventors of the instant invention are also the inventors of an invention entitled DIESEL TUNE UP METHOD, patented on Oct. 24, 1989, and having U.S. Pat. No. 4,875,451.
Both that patent and the instant disclosure deal with evening the power output among the cylinders of a fuel injected engine, particularly diesel engines. The prior invention dealt with the older style injection engines which were not electronically controlled. In those engines, the amount of fuel per injection stroke that each cylinder receives is dependent on the particular injector which operates with that cylinder. The above-referenced patent disclosed a method whereby high flowrate injectors are assigned to the lower compression cylinders to increase their compression and temperature, and low flowrate injectors were assigned to high temperature cylinders.
The leveling of the power delivery among the cylinders has produced dramatic improvements in fuel economy as demonstrated in extensive tests. Although not documented extensively, the engines also run more smoothly, and it is likely that by removing the jarring effect on the engine of uneven cylinder combustion, the life of the engine will be extended.
In the new generation of diesel engines and other fuel injected engines, the injectors are controlled by an electronic control module (ECM). The ECM timing of the injectors from a reference signal input from a magnetic trigger on the fly wheel. Ambient air pressure is also monitored and input to the ECM so that as the vehicle is driven up into the mountains, for example, the rate of fuel injection is decreased with the decrease in air pressure so that fuel does not remain unburned in the cylinders and be expelled through the exhaust as blue or black smoke. Applicants attorney has a diesel and can attest to this problem. At altitudes, he has been yelled at by other motorists, and on one occasion, in a ski area parking lot at about 9,000 feet, he was actually "stoned" with snowballs by complete strangers. The same vehicle operates virtually smoke-free at sea level.
The ECM also receives an input from the throttle (i.e. the accelerator petal) and factors this input into the injector settings. Thus, there is no direct mechanical or hydraulic control of the fuel flow rate at all. Anything that would effect the flow rate is input into the electronic control module, which then calculates the appropriate fuel flow-rate for the injectors, and signals the electronic distributor unit which includes drivers for the respective solenoids of the individual injectors.
The newer electronic controls no doubt result in improved engine performance and are hopefully reliable, as road repairs are generally impossible without replacement chips. Also, because the fuel delivered per injection is controlled by the ECM, it is no longer possible to effect the uniform power distribution among cylinders by physically allocating specific injectors to specific cylinders as was done according to the disclosure of the above-referenced patent.